Marine Engine Oil Types

Marine oils are more diversified than the motor oil that you have to change according to your outboard's maintenance schedule. They include the greases that lubricate the tilt land trim system, turbine oils used on any turbocharged motors and the gear lubricants used in marine gear boxes, lower units and outboard gear cases.

  1. Motor Oil

    • "Motor oil" is a catch-all phrase that covers the oil used in both the forced-lubrication systems of engines that have a reservoir of oil that recirculates through the engine during operation and oil in 2-stroke engines that use a of mix oil and fuel to lubricate the engine. The characteristics of these oils are similar to those of an automobile engine, but because marine motor oils face harsher conditions and are used in the marine environment, they must be changed every 200 operating hours, rather than after a specific number of miles.

    Gear Oil

    • Gear oil, the oil found in the gear case of an outboard motor, the lower units of an inboard-outboard boat or the gear box of an inboard motor is heavier -- that is, of a thicker consistency -- than the oil found in an engine. Where the motor oil that lubricates the engine is pourable, gear oil must be pumped into the gear case or gear box, using a specialized gear oil pump.

    Turbine Oil

    • Turbine oil is a relatively thin oil used to lubricate the turbines found in the turbochargers of marine engines. Many of the marine engines that use turbochargers are those that operate in an ocean environment. The close tolerances found in these turbines require a marine oil that is thin, rather than thick. Turbine oil is a low-viscosity oil; many are straight mineral oils with an anti-corrosive additive to counter the effects of operating in a saltwater environment.

    Other Lubricants

    • The other marine oil products include the specialty oils and greases used in the water pump of outboard motors and the greases used to lubricate the large moving parts, such as the swivel bracket on the motor mount.

      Anti-seize lubricants are used to prevent corrosion that may lock fasteners in place. Penetrating oils help in the removal of fasteners that do become locked in place by both corrosion and salt from the marine environment.

      Dielectric grease is used to seal electrical connections, preventing the high humidity air of the marine environment from dispensing a load of corrosion-causing atmospheric moisture on exposed electrical terminals and solder joints.